1. Field of the Invention
The present invention relates to a built-in antenna mounting structure and a shielding structure for portable radio equipment such as a portable telephone and a cordless telephone.
2. Description of the Related Art
In recent years, portable radio equipment such as a portable telephone has widely been put to practical use in response to an increase in communications demand. Portable radio equipment usually includes an antenna built in a housing of the equipment, so as to ensure a receiving function in carrying the equipment. The built-in antenna is required to be fit for a reduction in size and weight of the equipment and excellent in assemblability, based on a premise that desired electrical characteristics on resonance frequency, bandwidth, gain, etc. have been obtained.
Further, in response to the requirement of a reduction in size and weight of the portable radio equipment, it is necessary to use a thin-walled case, in which many high-density mounted electronic components are accommodated. Such portable radio equipment uses a high-frequency band ranging from about 800 to 900 MHz, which is called a quasi-microwave band. Accordingly, it is necessary to intensify electromagnetic shield in the case reduced in weight and thereby prevent various troubles due to electromagnetic interference.
As a built-in antenna in a conventional portable telephone, a platelike inverted F-shaped antenna is known. The inverted F-shaped antenna is directly mounted on a printed wiring board to ensure a receiving function during standby. Further, a conventional shielding structure for a portable telephone is provided by soldering a U-shaped spring to a ground pattern on a printed wiring board, forming a metal film by plating, electrostatic coating, aluminum deposition, etc. on the inner surface of a molded resin case having a rib, and engaging the U-shaped spring with the rib to bring the spring into contact with the inner surface of the case.
However, in the conventional built-in antenna mounting structure as mentioned above, the built-in antenna is mounted on the printed wiring board, so that a component mounting region on the printed wiring board cannot be easily ensured, causing a difficulty of size reduction and thickness reduction of the portable radio equipment. Further, in the conventional shielding structure, the U-shaped spring is soldered to the printed wiring board, so that a man-hour for mounting the spring is increased, and this shielding structure cannot support high-density mounting.